September
Monthly climate
ENSO & SST
Forecast validation
Three-month outlook
Feature article
Tropical Pacific rainfall
Data sources
Pacific Islands Climate Prediction Project
Janita Pahalad, Australian Bureau of Meteorology
Introduction
In 2001 a needs analysis for strengthening Pacific Islands meteorological services found that was of the National Meteorological Services (NMSs) in the region were encountering many difficulties in providing basic services for the citizens and industries of their countries. One of the clear priorities was the need to enhance the ability of NMSs to provide seasonal climate prediction services.
Forecast validation: June to August 2005
Enhanced convection and above average rainfall was expected over Eastern Kiribati, with near or above average rainfall forecast for Western Kiribati and Tuvalu. Suppressed convection with average or below average rainfall was expected over the Marquesas Islands and Fiji. Near average rainfall was expected elsewhere in the region.
Areas of above average rainfall occurred from Tonga east to Southern French Polynesia.
ENSO and Sea Surface Temperatures
The tropical Pacific Ocean is in a neutral state (no El Niño or La Niña), although equatorial Pacific sea surface temperature (SST) anomalies remain positive. The Southern Oscillation Index (SOI) was negative in August (–0.9), mainly as a result of higher pressures at Darwin, but the 3- month June–August mean was near zero (–0.2). The NINO3, NINO4, and NINO3.4 SST anomalies in August were all near +0.5 °C, which is slightly cooler than they have been the past three months.
Climate developments in August 2005
The South Pacific Convergence Zone (SPCZ) extended from Papua New Guinea to the region south of Tuvalu (due to enhanced convection near Papua New Guinea), with areas of associated convection northeast of Fiji and also towards Pitcairn Island. North of the equator, the Intertropical Convergence Zone (ITCZ) was quite active, extending eastward from the region near the Marshall Islands across to South America.
Tropical rainfall outlook: September to November 2005
Enhanced convection is likely over the Solomon Islands, where rainfall is expected to be above average. A region of near or above average rainfall is expected over Papua New Guinea. Another region of near or above average rainfall extends from the Marquesas Islands west to Samoa including the Tuamotu Islands, the Southern Cook Islands, and Niue.
Suppressed convection is expected from Vanuatu to Fiji, including Tuvalu, and also over Eastern Kiribati.
Tropical pacific rainfall - August 2005
Territory and station name
August 2005 rainfall total (mm)
Long-term average (mm)
August 2005 percent of average
Lowest on record (mm)
Highest on record (mm)
Records began
American Samoa
Pago Pago Airport
343.1
174
197
7
437
1966
Australia
Cairns Airport
58.6
27
217
0
140
1941
Townsville Airport
45.0
13
346
0
258
1940
Brisbane Airport
25.4
43
59
0
126
1929
Sydney Airport
1.4
79
2
1
378
1929
Cook Islands
Penryhn
40.6
193
21
21
613
1937
Rarotonga Airport
97.7
109
90
7
475
1929
Rarotonga EWS
99.
An overview of the present climate in the tropical South Pacific Islands, with an outlook for the coming months, to assist in dissemination of climate information in the Pacific region.
Number 60 – September 2005
August's climate: South Pacific Convergence Zone extended from Papua New Guinea to the south of Tuvalu. Well above average rainfall in parts of New Caledonia and central French Polynesia; below average rainfall in the northern Cook Islands and northern New Zealand.
Sources of South Pacific rainfall data
This bulletin is a multi-national project with important collaboration from the following Pacific nations:
American Samoa
Australia
Cook Islands
Fiji
French Polynesia
Kiribati
New Caledonia
New Zealand
Niue
Papua New Guinea
Pitcairn Island
Samoa
Solomon Islands
Tokelau
Tonga
Tuvalu
Vanuatu
Requests for Pacific island climate data should be directed to the Meteorological Services concerned.
Acknowledgements
This bulletin is made possible with financial support from the New Zealand Agency for International Development (NZAID), Wellington, New Zealand, wi